1. Field of the Invention
The present invention relates to communication apparatus connecting at least a mail server and clients over a communication network and performing e-mail communication via the mail server, and e-mail communication method suitable for such apparatus.
2. Description of the Related Art
Recently, prevailing of communication networks such as internet is remarkable. Even personal computers in houses use WWW (World Wide Web), e-mail, network news, etc. very frequently.
In offices, a communication network such as LAN connects a router for connection to the internet, a mail server, a facsimile server and clients, thereby establishing a communication network system. When the facsimile server receives data from a client, it transfers data (e.g., facsimile image data and e-mail) over PSTN or to the mail server based on designation of recipient (e.g., facsimile number and e-mail address) made by the client.
This type of facsimile server has an ordinary facsimile function so that it can also transmit image, which is scanned by an associated scanner, to a remote facsimile machine or a remote party in the form of e-mail.
The e-mail communication over the internet has specifications defined by RFC (request for comments). According to RFC, an e-mail transmitter can have an optional function of receiving a return e-mail that notifies reception of the e-mail. This reception acknowledgement (return receipt) is either MDN (Message Disposition Notification) or DSN (Delivery Status Notification). MDN is set to a respective e-mail by the transmitter, and DSN is set to the mail server by a command from the transmitter.
MDN notifies that a recipient of an e-mail has received (or printed or seen) the e-mail. On the other hand, DSN is a notification returned from a mail server at the most downstream stage of the network. DSN is sent back from a recipient provider that has a mail server, if the e-mail has properly reached the recipient. If the e-mail is not delivered to the recipient, a server where malfunctioning occurs issues a failure notification.
The above described network system has the following problems. The facsimile server receives image data from a client and sends it in the form of e-mail. The facsimile server can also scan image data with its scanner and send it in the form of e-mail. These two e-mails are accompanied by an address of the facsimile server. Thus, the receipt acknowledgement is directed to the address of the facsimile server. Accordingly, when the facsimile server sends the scanned data, the reception acknowledgement is returned to the correct data transmitter. On the other hand, however, when the facsimile server transfers the data from the client, the acknowledgement is not returned to the correct data origin, i.e., client, but the relay station, i.e., facsimile server, since the facsimile server cannot identity the client.